The present invention relates to an antenna apparatus using a slot, and more specifically, relates to an antenna apparatus, which makes it possible to consolidate a plurality of slot antennas, has a polarization diversity function and a simple construction of feed means, and is small, sophisticated and highly efficient, and is capable of obtaining a broadband property.
Antenna elements can be constructed by forming a so-called straight-line slot exhibiting a straight line on a conductive plate, the face of which being overlapped on a dielectric plate. Then, by feeding power from a signal source (source) to the slot, the electromagnetic field resonates in the slot to thereby radiate radio wave. The slot antenna (antenna apparatus) having such a kind of straight-line slot has excellent electric characteristics, and hence is used in a wide range of application.
The slot antenna, however, is used functionally as a single antenna, and it is difficult to use it as a polarization diversity antenna.
It is also difficult to arrange a plurality of slot antennas close to each other, due to a restriction such as antenna size, etc.
If a plurality of slot antennas is arranged in a space as small as being occupied by only one slot antenna, the electrical effect between antennas increases. Therefore, practical use of such an antenna consolidating a plurality of slot antennas has been difficult.
Moreover, at the time of realizing an antenna consolidating a plurality of slot antennas, simple construction of the feed mean, miniaturization, improvement in the performance and efficiency, and obtaining broadband property are important.
It is therefore an object of the present invention to provide an antenna apparatus, which solves the above problems, makes it possible to consolidate a plurality of slot antennas, has a polarization diversity function and a simple construction of the feed means, and is small, sophisticated and highly efficient, and is capable of obtaining a broadband property.
According to the first feature, an antenna apparatus comprises a pair of antenna elements constituted by forming a slot on a conductive plate overlapped on a dielectric plate, wherein the pair of antenna elements orthogonal of each other is constituted by forming a slot having a crossing at which two linear portions extending straight with a predetermined width cross at right angles, at the center in the longitudinal direction to each other, and having fan-shaped portions at opposite ends of each linear portion, expanding gradually than the width of the linear portion.
A first feeder line forming an angle of +45xc2x0 with respect to one linear portion and a second feeder line forming an angle of xe2x88x9245xc2x0 with respect to this linear portion are provided along the dielectric plate so as to pass through the crossing, respectively, and in the vicinity of the crossing, one feeder line may be arranged on one face of the dielectric plate and the other feeder line may be arranged on the opposite face of the dielectric plate.
A reflecting plate consisting of a conductor may be provided with a predetermined distance separated from a face opposite to the face of the dielectric plate where the conductive plate is overlapped.
An electric characteristic adjusting plate consisting of a conductor may be provided with a predetermined distance separated from a face opposite to the face of the conductive plate overlapping on the dielectric plate.
A slot may be formed in the electric characteristics adjusting plate.
A plurality of the pairs of antenna elements may be provided on the conductive plate.
The plurality of pairs of antenna elements provided on the conductive plate may be arranged in series.
A feeder line may be provided for feeding power in parallel to each of the plurality of pairs of antenna elements.
According to the second feature, an antenna apparatus comprises a pair of antenna elements constituted by forming a slot on a conductive plate overlapped on a dielectric plate, wherein the pair of antenna elements is constituted by forming a slot having a shape such that two linear portions extending straight with a predetermined width cross at right angles, at the center in the longitudinal direction of each other, and a first feeder line forming an angle of +45xc2x0 with respect to one linear portion and a second feeder line forming an angle of xe2x88x9245xc2x0 with respect to said linear portion are provided along said dielectric plate so as to pass through said crossing of said two linear portions, respectively, and in the vicinity of said crossing, one feeder line is arranged on one face of said dielectric plate and the other feeder line is arranged on the opposite face of said dielectric plate.
The present invention exhibits excellent effects as described below.
(1) Since slots are formed such that slots comprising a linear portion and a fan-shaped portion at the end thereof cross each other in a shape of a cross, the polarization diversity function can be provided.
(2) Since two feeder lines are arranged on the front face and on the back face of the dielectric plate at the crossing, the construction of the feed means becomes simple.
(3) Since two linear slot antennas are arranged so as to cross each other, two slot antennas are consolidated in the same space, thereby enabling space saving, that is, miniaturization.
(4) Since two linear slot antennas are arranged in a perpendicular alignment, thereby enabling improvement in performance, such that the influence to each other becomes small, high S/N ratio can be obtained, and directivity becomes wide.
(5) Since the reflecting plate is arranged, a highly efficient antenna can be realized.
(6) Since the electric characteristics adjusting plate is installed, broadband property can be obtained.